Blue anthrarufin dye and process of making same.



rrn SATES PATENT FFlClJ.

ROBERT E. SCHMIDT AND PAUL TUST, OF ELBERFELD, GERMANY, ASSIGNORS TO THEFARBENFABRIKEN OF ELBERFELD COMPANY, OF NEW YORK, N. Y.

BLUE ANTHRARUFIN DYE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 656,670, dated August28, 1900. Application filed August 25, 1899. Serial No. 728,398.(Specimensd To all whom it may concern.-

Be it known that we, ROBERT E, SoHMnor, doctor of philosophy, chemist,and PAUL TUsT, chemist, both residing at Elberfeld, Ger= many,(assignors to the FARBENFABRIKEN on ELBERFELD COMPANY, of New York,)have invented a new and useful Improvement in Blue Anthrarufin Dye; andwe hereby declare the following to be a clear and exact description ofour invention.

Our invention relates to the production of a new blue dyestuft, which isa monosulfonic acid of monobromdiamidoanthrarufin, by heatingmonobromdinitroanthrarufinmond sulfonic acid with suitable reducingagents. The monobromdinitroanthrarufinmonosulfonic acid employed asstarting material in our new process has the following properties It isan orange crystalline powder, which dissolves in water with a yellowcolor and in a dilute soda-lye with a yellowish-red color. Byconcentrated sulfuric acid it is dissolved with a yellow color. If boricacid is added to the sulfuric-acid solution, the color changes into red.On heating this solution the color is transformed into reddish violet.The solution thus obtained exhibits an absorption spectrum which ischaracterized by two weak lines in its green and in its yellow part.

In carrying out our new process practically we may proceed as follows,the parts being by weight: To'a solution of twenty parts ofn1onobromdinitroanthrarufin monosulfonic acid in two thousand parts ofwater a solution prepared from forty-eight parts of stannous chlorid,one hundred and thirty parts of concentrated hydrochloric acid, and onehundred and thirty parts of water is added at about from to centigrade.Afterashort while the color of the mixture will change into blue, thegreaterpart of the new diainido acid being separated during thereaction. When the reduction is finished, a hundred parts ofhydrochloric acid are added. Subsequently the new dyestuft is isolatedby filtration. Finally it is pressed, dried, and pulverized. It is thusobtained in the shape of a dark-blue powder which is difficultly solublein water with a blue color and soluble in dilute alkalies with'a colorvarying from blue to greenish blue. By concentrated sulfuric acid it isdis solved with a yellow color, which on the addition of boric acidchanges at first into red and then after a while into blue. This bluesolution exhibits a spectrum which is characterized by two lines in itsred and in its yellow part. i

The new coloring-matter dyes un mordanted wool in acid-baths bright-blueshades, while it yields on chrome mordanted wool bright and fastgreenish-blue shades.

Having now described our invention and in what manner the same is to beperformed, what we claim as new, and desire to secure by Letters Patent,is-- 1. The process for producing a new blue dyestufi beingamonobromdiamidoanthrarufinmonosulfonic acid, which process consists infirst heating a mixture prepared from monobromdinitroanthrarufinmonosulfonic acid, stannous chlorid and hydrochloric acid,secondly isolating the dyestuft thus produced by filtration and finallydrying the same, substantially as hereinbefore described.

2. As a new article of manufacture the new dyestuif being amonobromdiamidoanthrarufinmonosulfonic acid, which when dry andpulverized is a dark-blue powder, diflicultly soluble in Water with ablue color, soluble in dilute alkalies with a color varying from blue togreenish blue, being dissolved by concentrated sulfuric acid with ayellow color which on the addition of boric acid changes first into redand then after a while into blue, dyeing unmordanted wool in acid-bathsbright-blue shades, while it yields on chrome mordanted wool bright andfast greenish-blue shades, substantially as hereinbefore described.

In testimony whereof we have signed our names iuthe presence of twosubscribing witnesses.

ROBERT E. SCHMIDT.

PAUL TUST. Witnesses:

R. E. J AHN, Orro Komc.

